Deposit protection cover and plasma processing apparatus

ABSTRACT

There are provided a deposit protection cover and a plasma processing apparatus capable of providing a simple solution to deposits adhered to a portion originally considered to be unreachable by plasma without increasing manufacturing cost. The deposit protection cover is detachably installed within a processing chamber for processing a substrate by generating plasma therein so as to cover a preset portion of the processing chamber. The cover includes an aluminum plate having a surface on which an anodic oxidation process is performed. Further, the anodic oxidation process is performed by using an electrode part protruded from a cover main body, an exposed area of an aluminum base surface is reduced by removing the electrode part after the anodic oxidation process is performed, and a cut surface formed after removing the electrode part is positioned at a region that is not directly exposed to the plasma within the processing chamber.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Japanese Patent Application No.2009-175777 filed on Jul. 28, 2009, and U.S. Provisional ApplicationSer. No. 61/238,266 filed on Aug. 31, 2009, the entire disclosures ofwhich are incorporated herein by reference.

FIELD OF THE INVENTION

The present disclosure relates to a deposit protection cover and aplasma processing apparatus.

BACKGROUND OF THE INVENTION

Conventionally, in the field of manufacture of semiconductor devices orthe like, there is known a plasma processing apparatus that processes atarget substrate such as a semiconductor wafer by generating plasmawithin a hermetically sealable processing chamber. Further, there isknown a plasma etching apparatus as one example of such a plasmaprocessing apparatus.

In such a plasma etching apparatus or the like, plasma etching may causedeposits to adhere on the inside of the processing chamber. The depositsmay be peeled off from the inside of the processing chamber and, then,the deposits may be dispersed as particles and be adhered to asemiconductor wafer on which an etching process is being performed. Toprevent this problem, conventionally, the inside of the processingchamber has been cleaned periodically.

Further, a cylindrical liner is installed so as to cover a wallsurrounding a plasma generation space in the processing chamber, and,then deposits are removed from the inside of the processing chamber byregularly replacing or cleaning the liner after separating the liner(see, for example, Patent Document 1).

Patent Document 1: Japanese Patent Laid-open Publication No. 2008-270595

As stated above, conventionally, the cylindrical liner or the likecovering the wall surrounding the plasma generation space has beeninstalled and the liner has been regularly replaced or separated andcleaned.

However, deposits may be adhered not only to the plasma generation spaceof the processing chamber but also to a portion originally considered tobe unreachable by plasma, such as a portion under a baffle plateconfigured to surround a mounting table for mounting a target substratethereon and provided with a through hole, a slit, or the like throughwhich a gas exhaust is performed. If deposits are adhered to such aportion and if it is difficult to separate and clean components of theprocessing chamber, it has been difficult to completely remove thedeposits by performing a cleaning process within the processing chamber.Therefore, there has been a problem that it takes a long time tocomplete the cleaning process.

Furthermore, to install a detachable cover configured to cover such aportion, at least a surface of the cover needs to be made of aninsulating material so as to prevent an abnormal electric discharge, anda highly plasma-resistance material should be used for the cover.Therefore, there has been a problem that manufacturing cost isincreased.

BRIEF SUMMARY OF THE INVENTION

In view of the foregoing, in order to solve the above-mentioned problem,the present disclosure provides a deposit protection cover capable ofproviding a simple solution to deposits adhered to a portion originallyconsidered to be unreachable by plasma without increasing manufacturingcost, and also provides a plasma processing apparatus using the same.

In accordance with a first embodiment of the present disclosure, thereis provided a deposit protection cover detachably provided within aprocessing chamber so as to cover a preset portion of the processingchamber that processes a substrate by generating plasma therein. Thecover includes an aluminum plate having a surface on which an anodicoxidation process is performed. Further, the anodic oxidation process isperformed by using an electrode part protruded from a cover main body,an exposed area of an aluminum base surface is reduced by removing theelectrode part after the anodic oxidation process is performed, and acut surface formed after removing the electrode part is positioned at aregion that is not directly exposed to the plasma within the processingchamber.

In accordance with a second embodiment of the present disclosure, thereis provided a plasma processing apparatus including a processing chamberand processing a substrate by generating plasma therein. The apparatusincludes a deposit protection cover made of an aluminum plate having asurface on which an anodic oxidation process is performed, and the coveris detachably provided within the processing chamber so as to cover apreset portion of the processing chamber. Further, the anodic oxidationprocess is performed by using an electrode part protruded from a covermain body, an exposed area of an aluminum base surface is reduced byremoving the electrode part after the anodic oxidation process isperformed, and a cut surface formed after removing the electrode part ispositioned at a processing chamber's portion a region that is notdirectly exposed to the plasma within the processing chamber.

In accordance with the above-mentioned present disclosure, there areprovided a deposit protection cover and a plasma processing apparatuscapable of providing a simple solution to deposits adhered to theportion originally considered to be unreachable by plasma withoutincreasing manufacturing cost.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may best be understood by reference to the followingdescription taken in conjunction with the following figures:

FIGS. 1A and 1B are schematic diagrams illustrating a configuration of adeposit protection cover in accordance with an embodiment of the presentdisclosure;

FIG. 2 is a schematic diagram illustrating a configuration of a plasmaetching apparatus in accordance with an embodiment of the presentdisclosure;

FIG. 3 is a schematic diagram illustrating a configuration of majorparts of the plasma etching apparatus of FIG. 2;

FIG. 4 is a schematic diagram illustrating a configuration of majorparts of the plasma etching apparatus of FIG. 2; and

FIGS. 5A and 5B are diagrams for describing usage states of the depositprotection cover of FIGS. 1A and 1B.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the present disclosure will be describedwith reference to the accompanying drawings.

FIGS. 1A and 1B are diagrams for describing a configuration of a depositprotection cover 110 in accordance with an embodiment of the presentdisclosure. The deposit protection cover 110 shown in FIGS. 1A and 1B ismade of an aluminum plate in a predetermined shape.

As illustrated in FIG. 1A, the deposit protection cover 110 in themiddle of manufacture is provided with an electrode part 112 protrudingfrom a cover main body 111 so as to be used when an anodic oxidationprocess is performed. An anodically oxidized film is formed on the covermain body 111 of the deposit protection cover 110 by performing theanodic oxidation process. Meanwhile, since the electrode part 112 isused as an electrode when the anodic oxidation process is performed,anodically oxidized film is not formed on its surface, and an aluminumbase surface is just exposed.

Accordingly, in the embodiment shown in FIG. 1B, the electrode part 112is removed after the anodic oxidation process is performed on the covermain body 111 of the deposit protection cover 110, and the depositprotection cover 110 is used without the electrode part 112.

Accordingly, in a state shown in FIG. 1B, an aluminum base surface isexposed only at a cut surface 112 a formed after the electrode part 112is removed. As compared to a state before the removal of the electrodepart 112 of FIG. 1A, an exposed area of the aluminum base surface isreduced. Further, the cut surface 112 a is formed so as to be positionedat a portion which is not directly exposed to plasma when the depositprotection cover 110 is provided within a processing chamber of a plasmaetching apparatus or the like, as will be described later. By thedeposit protection cover 110 in such a state, a risk of an abnormalelectric discharge can be reduced.

Furthermore, by using the aluminum plate of which surface is anodicallyoxidized as state above, manufacturing cost can be reduced as comparedto, e.g., a case of forming highly plasma-resistant fine ceramics on anentire metal plate by thermal spraying.

Referring to FIG. 2, a configuration of a plasma processing apparatus(plasma etching apparatus in the present embodiment) in which thedeposit protection cover 110 having the above-described configuration isprovided will now be explained. The plasma etching apparatus includes asubstantially cylindrical processing chamber 2 made of, e.g., aluminumof which surface is anodically oxidized. The processing chamber 2 isgrounded.

A substantially cylindrical susceptor support 4 configured to mount asemiconductor wafer W thereon is installed at a bottom portion of theprocessing chamber 2 via an insulating plate 3 made of, e.g., ceramics.A susceptor (mounting table) 5 serving as a lower electrode is installedon the susceptor support 4. A high pass filter (HPF) 6 is connected withthe susceptor 5.

A coolant path 7 is provided within the susceptor support 4, and acoolant is circulated through the coolant path 7 after introduced to acoolant introduction line 8 and is discharged through a coolantdischarge line 9. A cold heat is transferred to the semiconductor waferW via the susceptor 5, and, thus the semiconductor wafer W may beadjusted to a desired temperature.

The susceptor 5 is formed in a circular plate shape having a protrudedupper central portion, and a circular electrostatic chuck 11 having thesubstantially same diameter as that of the semiconductor wafer W isprovided on the protruded upper central portion of the susceptor 5. Theelectrostatic chuck 11 includes an electrode 12 embedded in aninsulating material. Further, a DC voltage of, e.g., about 1.5 kV isapplied to the electrode 12 from a DC power supply 13, and, thus, thesemiconductor wafer W can be electrostactically attracted and held by,e.g., Coulomb force.

A gas passage 14 for supplying a heat transfer medium (for example, a Hegas) to a rear surface of the semiconductor wafer W is formed throughthe insulating plate 3, the susceptor support 4, the susceptor 5, andthe electrostatic chuck 11. Cold heat of the susceptor 5 is transferredto the semiconductor wafer W through the heat transfer medium, and,thus, the semiconductor wafer W can be maintained at a presettemperature.

An annular focus ring 15 is provided at an upper peripheral portion ofthe susceptor 5 so as to surround the semiconductor wafer W mounted onthe electrostatic chuck 11. The focus ring 15 is made of a conductivematerial such as silicon and can improve etching uniformity.

An upper electrode 21 is provided above the susceptor 5, facing thesusceptor 5 in parallel. The upper electrode 21 is held on an upperportion of the processing chamber 2 via an insulating member 22. Theupper electrode 21 includes an electrode plate 24; and an electrodesupport 25 made of a conductive material and configured to hold theelectrode plate 24. The electrode plate 24 is made of a semiconductor ora conductor, such as Si or SiC, and has a plurality of discharge holes23. The electrode plate 24 forms a facing surface toward the susceptor5.

A gas inlet port 26 is provided in a center of the electrode support 25of the upper electrode 21, and a gas feed pipe 27 is coupled to the gasinlet port 26. Further, the gas feed pipe 27 is connected with aprocessing gas feed source 30 via a valve 28 and a mass flow controller29. The processing gas feed source 30 feeds an etching gas for a plasmaetching process.

An exhaust pipe 31 is coupled to a bottom portion of the processingchamber 2, and the exhaust pipe 31 is connected with an exhaust unit 35.The exhaust unit 35 includes a vacuum pump such as a turbo-molecularpump and serves to evacuate the inside of the processing chamber 2 to apreset pressure of, e.g., about 1 Pa or less. Therefore, the exhaustunit 35 can create a preset depressurized atmosphere within theprocessing chamber 2. Further, a gate valve 32 is provided at a sidewall of the processing chamber 2. After the gate valve 32 is opened, thesemiconductor wafer W may be transferred to/from an adjacent load-lockchamber (not illustrated).

The upper electrode 21 is coupled to a first high frequency power supply40 via a matching unit 41. Further, the upper electrode 21 is alsoconnected with a low pass filter (LPF) 42. The first high frequencypower supply 40 has a frequency ranging from about 27 MHz to about 150MHz. By applying a high frequency power in such a high frequency range,high-density plasma in a desirable dissociation state can be generatedwithin the processing chamber 2.

The susceptor 5 serving as a lower electrode is coupled to a second highfrequency power supply 50 via a matching unit 51. The second highfrequency power supply 50 has a frequency lower than that of the firsthigh frequency power supply 40. By applying a high frequency power insuch a frequency range, an appropriate ionic action can occur withoutinflicting damage on the semiconductor wafer W serving as a targetsubstrate. Desirably, the frequency of the second high frequency powersupply 50 may be in the range of, e.g., about 1 MHz to about 20 MHz.

Further, a deposit shield 80 may be detachably provided along an innerwall of the processing chamber 2 so as to prevent adhesion of an etchingby-product (deposits) to the processing chamber 2. That is, the depositshield 80 may form a processing chamber wall. The deposit shield 80 maybe also provided at outer peripheral portions of the susceptor support 4and the susceptor 5. Furthermore, in the vicinity of a bottom portion ofthe processing chamber 2, a baffle plate (exhaust plate) 83 may beprovided between the deposit shield 80 on the processing chamber walland the deposit shield 80 on the susceptor support 4. The depositshields 80 and the baffle plate 83 can be fabricated by coating analuminum material with ceramics such as Y₂O₃. The baffle plate 83 isprovided with through holes or slits for gas exhaust. The baffle plate83 can uniformly exhaust gas through a circular ring-shaped regionaround the susceptor 5 and be configured to suppress reaching of plasmainto a downstream of the baffle plate 83.

In the present embodiment, a deposit protection cover 110 is provided soas to cover a certain portion below the baffle plate 83. That is, asshown in FIG. 3, besides exhaust path portions provided with exhaustpaths 120, non-exhaust-path portions 121, 122 and 123 provided withoutexhaust path 120 exist below the ring-shaped baffle plate 83 due tostructural restriction. The deposit protection covers 110 having shapescorresponding to the shapes of the non-exhaust-path portions 121, 122and 123 are detachably installed at the respective non-exhaust-pathportions 121, 122 and 123. Furthermore, FIG. 4 is a partial verticalsectional perspective view illustrating the processing chamber 2's partshown in FIG. 3.

As shown in FIG. 5A, depending on a process performed in the processingchamber 2, deposits may be adhered to the non-exhaust-path portions 121,122 and 123 by, e.g., plasma that reaches the non-exhaust-path portionsthrough the through holes of the baffle plate 83. Since, however, plasmatypically does not reach the portions below the baffle plate 83, thoseportions have not been considered to be portions to which deposits areadhered. Thus, if deposits 130 are adhered to such portions, thoseportions cannot be separated to be cleaned. Therefore, when thoseportions in the narrow processing chamber 2 need be cleaned, it may takea long time to complete the cleaning and the deposits may not becompletely removed.

Meanwhile, in the present embodiment, as shown in FIG. 5B, since thenon-exhaust-path portions 121, 122 and 123 are covered with the depositprotection covers 110, deposits, if any, may be adhered to the depositprotection covers 110, and the deposit protection covers 110 can bereplaced or cleaned easily after separated.

The overall operation of the plasma etching apparatus configured asdescribed above is controlled by a control unit 60. The control unit 60includes a process controller 61 having a CPU for controlling eachcomponent of the plasma etching apparatus; a user interface 62; and astorage unit 63.

The user interface 62 includes a keyboard with which a process managerinputs commands to manage the plasma etching apparatus; and a display onwhich an operational status of the plasma etching apparatus is visuallydisplayed.

The storage unit 63 stores therein control programs (software) forexecuting various processes in the plasma etching apparatus under thecontrol of the process controller 61; and recipes including processingcondition data or the like. A necessary recipe may be retrieved from thestorage unit 63 and executed by the process controller 61 in response toan instruction from the user interface 62, and, thus, a desired processmay be performed in the plasma etching apparatus under the control ofthe process controller 61. Furthermore, the control programs or therecipes including the processing condition data or the like can beretrieved from a computer-readable storage medium (e.g., a hard disk, aCD, a flexible disk, or a semiconductor memory), or can be used on-lineby being transmitted from another apparatus via, e.g., a dedicated line,whenever necessary.

Before plasma etching is performed on a semiconductor wafer W by theplasma etching apparatus having the above-described configuration, thegate valve 32 is opened. Then, the semiconductor wafer W is loaded intothe processing chamber 2 from a load-lock chamber (not shown) andmounted on the electrostatic chuck 11. Thereafter, a DC voltage isapplied from the DC power supply 13, and, thus, the semiconductor waferW is electrostatically attracted and held on the electrostatic chuck 11.Subsequently, the gate valve 32 is closed, and the inside of theprocessing chamber 2 is evacuated by the exhaust unit 35 to a presetvacuum pressure level.

Thereafter, the valve 28 is opened, and a preset etching gas is fed intoa central portion of the upper electrode 21 through the gas feed pipe 27and the gas inlet port 26 from the processing gas feed source 30 whileits flow rate is controlled by the mass flow controller 29 and isuniformly discharged toward the semiconductor wafer W through thedischarge holes 23 of the electrode plate 24, as indicated by arrows inFIG. 2.

Then, the inside of the processing chamber 2 is maintained at a presetpressure. Thereafter, a high frequency power of a preset frequency isapplied to the upper electrode 21 from the first high frequency powersupply 40. As a result, a high frequency electric field is generatedbetween the upper electrode 21 and the susceptor 5 as the lowerelectrode, and the etching gas is dissociated and excited into plasma.

Meanwhile, a high frequency power of a frequency lower than that of thefirst high frequency power supply 40 is applied to the susceptor 5serving as the lower electrode from the second high frequency powersupply 50. As a result, ions in the plasma can be attracted toward thesusceptor 5, so that etching anisotropy can be improved by ion assist.

Upon completing the plasma etching process, the supply of the highfrequency power and the processing gas is stopped, and the semiconductorwafer W is unloaded from the processing chamber 2 in the reversesequence as described above.

Although the embodiment of the present disclosure has been described inthe above, the present disclosure is not limited to the above-statedembodiment but can be modified in various ways. For example, the plasmaetching apparatus is not limited to the parallel plate type apparatusthat applies dual frequency powers to the upper and lower electrodes asillustrated in FIG. 2. For example, the present disclosure is applicableto various kinds of plasma etching apparatuses such as a type thatapplies dual high frequency powers to a lower electrode or a type thatapplies a single high frequency power to a lower electrode, orapplicable to various kinds of other plasma processing apparatuses.

1. A deposit protection cover detachably provided within a processingchamber so as to cover a preset portion of the processing chamber thatprocesses a substrate by generating plasma therein, the covercomprising: an aluminum plate having a surface on which an anodicoxidation process is performed, wherein the anodic oxidation process isperformed by using an electrode part protruded from a cover main body,an exposed area of an aluminum base surface is reduced by removing theelectrode part after the anodic oxidation process is performed, and acut surface formed after removing the electrode part is positioned at aregion that is not directly exposed to the plasma within the processingchamber.
 2. The deposit protection cover of claim 1, wherein the presetportion includes an inseparable part of the processing chamber.
 3. Thedeposit protection cover of claim 2, wherein the preset portion is apart of a portion positioned below a baffle plate for gas exhaustconfigured to surround a mounting table that mounts thereon thesubstrate within the processing chamber.
 4. A plasma processingapparatus including a processing chamber and processing a substrate bygenerating plasma therein, the apparatus comprising: a depositprotection cover made of an aluminum plate having a surface on which ananodic oxidation process is performed, the cover being detachablyprovided within the processing chamber so as to cover a preset portionof the processing chamber, wherein the anodic oxidation process isperformed by using an electrode part protruded from a cover main body,an exposed area of an aluminum base surface is reduced by removing theelectrode part after the anodic oxidation process is performed, and acut surface formed after removing the electrode part is positioned at aregion that is not directly exposed to the plasma within the processingchamber.